Abstract
In the present study, photocatalysts such as copper oxide (CuO) and titanium dioxide (TiO2) were coupled with graphene oxide (GO) for the synthesis of visible light active CuO-GO/TiO2 composite photocatalyst for the decomposition of 2-chlorophenol (2-CP) and complex aromatics in the real dairy wastewater. Photocatalytically decomposed dairy wastewater was further purified by aerobic digestion. The results revealed that composite material shows improved 2-CP degradation, as 86% removal was achieved with k=0.0101min(-1) at pH 5.0. The effect of pollutant concentration showed that the decomposition of 2-CP increases with the increase in the irradiation time and decreases with the increase in the 2-CP concentration in the solution. The reusability test showed the high stability of CuO-GO/TiO2 composite where the 2-CP degradation was achieved 85.8% after the third run. For real dairy wastewater degradation, photocatalysis increases the solubilization of the organic matters and a 24% higher sCOD (from 5764 to 7536mg/L after 6h) was observed compared to photolysis (without catalyst) pretreatment. This improves the aerobic digestibility of dairy wastewater where tCOD was significantly lowered from 12747 to 134.8mg/L within 27days of the process. Overall, the present study revealed that the CuO-GO/TiO2 composite material could be an efficient catalyst for removal of toxic organic pollutants and treatment of dairy effluent, thus it can be applied in wastewater treatment plants with a dependency of extensively available visible light.